A kind of aviation kerosene liquid phase hydrogenation device shutdown treatment method

Abstract

The application discloses a kind of navigation coal liquid phase hydrogenation device shutdown processing method, comprising: (1) first reduce navigation coal raw material feed temperature, when temperature reduces, stop navigation coal raw material, supplementary hydrogen is introduced into liquid phase hydrogenation reactor by heating furnace, nitrogen and part of fuel gas are introduced into heating furnace simultaneously, and mixed gas after heating enters by reactor top, sweeps catalyst bed layer;(2) after a period of time, maximum supplementary hydrogen is introduced into liquid phase hydrogenation reactor bed layer interlayer hydrogen supplement pipeline, and enters catalyst bed layer from the lower part of reactor, and is swept;(3) close heating furnace fuel gas bypass valve, fuel gas no longer enters heating furnace and liquid phase hydrogenation reactor, after a period of time, close supplementary hydrogen, nitrogen continues to sweep and replace reactor, and hydrocarbon oil in catalyst bed layer is discharged from the bottom of reactor.The method effectively improves catalyst oil carrying effect during shutdown, shortens shutdown purging time, and can quickly complete liquid phase hydrogenation device shutdown process.

Description

Technical Field

[0001] This invention belongs to the field of petroleum refining, and specifically relates to a method for handling the shutdown of a jet fuel liquid phase hydrogenation unit. Background Technology

[0002] With the continuous development of the global air transport industry, the demand for aviation kerosene has been increasing in recent years. Hydrogenation technology is currently the most mature and reliable technology for producing high-quality aviation kerosene products and is widely used in the refining industry. At the same time, due to increasing market competition in the refining industry, the investment cost and operating expenses of hydrogenation units are relatively high. How to achieve the production of clean aviation kerosene products while reducing investment and operating costs is an important problem that urgently needs to be solved.

[0003] Against this backdrop, several domestic patent holders of hydrogenation technology have developed low-cost liquid-phase hydrogenation technology for jet kerosene. This technology eliminates the need for a hydrogen recirculation system in the reaction section, relying instead on hydrogen dissolved in the kerosene feedstock to provide the chemically required hydrogen for the hydrogenation reaction. It boasts advantages such as a simple process flow, low investment cost, small footprint, and low operating cost. However, the elimination of the circulating hydrogen compressor results in significantly longer downtime for the liquid-phase hydrogenation unit. During downtime, the low hydrogen supply necessitates prolonged hydrogen purging of the catalyst to remove residual oil, frequently leading to high levels of residual oil after catalyst removal. This severely impacts catalyst removal efficiency and regeneration effectiveness. Consequently, the downtime of jet kerosene liquid-phase hydrogenation units is significantly extended, negatively affecting the profitability of refineries and hindering the further promotion and application of jet kerosene liquid-phase hydrogenation technology.

[0004] CN102527448B discloses a method and apparatus for deoiling a catalyst. This method and apparatus are specifically designed for removing oil from catalysts, employing a hot nitrogen circulation method. It can complete catalyst deoiling in a short time, achieving a deoiling rate as high as 98.7%, meeting the needs of continuous production in chemical plants.

[0005] CN112725026B discloses a shutdown method for a hydrocracking unit. This method controls the reaction temperature in the cracking section by increasing the nitrogen content in the feedstock and the reaction temperature in the refining section, while simultaneously injecting ammonia into the feedstock in the cracking section. The feedstock is then shut off for cooling and depressurization. This method effectively reduces the damage to the hydrocracking catalyst activity caused by the shutdown process, mitigating the problem of shortened service life of the hydrocracking unit after restarting.

[0006] However, none of the above patented technologies are shutdown methods for the liquid phase hydrogenation process of aviation kerosene. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for handling the shutdown of a liquid-phase hydrogenation unit for aviation kerosene. This method effectively improves the oil carryover effect of the hydrogenation catalyst during shutdown, shortens the shutdown purging time, and can quickly complete the shutdown process of the liquid-phase hydrogenation unit, effectively solving the problem of significantly prolonged shutdown time caused by the small amount of hydrogen purging gas in the liquid-phase hydrogenation unit.

[0008] The shutdown procedure for the liquid-phase hydrogenation unit of aviation kerosene of the present invention includes the following:

[0009] (1) First, reduce the feed temperature of aviation kerosene. When the temperature drops, stop feeding aviation kerosene. Add hydrogen by introducing it into the liquid phase hydrogenation reactor before the heater. At the same time, introduce nitrogen and some fuel gas before the heater. The mixed gas of heated nitrogen, hydrogen and some fuel gas enters the catalyst bed from the top of the liquid phase hydrogenation reactor to purge the catalyst bed. (2) Introduce the maximum amount of supplementary hydrogen into the hydrogen supply line between the liquid phase hydrogenation reactor beds and purge the catalyst bed from the middle and lower part of the reactor. (3) Close the fuel gas bypass valve of the heater. The fuel gas no longer enters the heater and the liquid phase hydrogenation reactor. Close the supplementary hydrogen. Nitrogen continues to purge and replace the reactor for 4 to 8 hours. The hydrocarbon oil in the catalyst bed is discharged from the bottom of the reactor.

[0010] In the method of the present invention, step (1) involves reducing the feed temperature to 210-280°C or 10-30°C below the final reaction temperature.

[0011] In the method of this invention, the nitrogen gas is the nitrogen gas commonly used in the nitrogen pipeline network of oil refining enterprises, mainly used for processes such as system replacement and drying.

[0012] In the method of this invention, the fuel gas mentioned in step (1) is a mixed gas supplied to the heating furnace of this device, and its main components include hydrogen, methane, ethane and a small amount of propane, butane, etc. The fuel gas introduced into the liquid phase hydrogenation reactor accounts for 30% to 80% of the total fuel gas in the feed heating furnace, and the remaining small amount of fuel gas is still used as fuel for the heating furnace to heat the mixed gas.

[0013] In the method of the present invention, in the mixed gas described in step (1), the proportion of nitrogen is 15-30%, the proportion of fuel gas is 15-30%, the proportion of supplemented hydrogen is 40-70%, and the mixed gas purging operation conditions are as follows: pressure 0.3-4.0 MPa, temperature 200-350℃, gas-fuel volume ratio 50-200, and purging time 2-4 hours.

[0014] In the method of this invention, the liquid-phase hydrogenation reactor in step (1) generally includes functional units such as a feed oil buffer tank, a feed pump, a feed heater, a gas-liquid mixer, a liquid-phase hydrogenation reactor, a low-pressure separator, a fractionation tower, and corresponding pipelines and valves. The liquid-phase hydrogenation reactor is a multi-bed fixed-bed hydrogenation reactor. The liquid-phase hydrogenation reactor can be a single reactor or multiple reactors connected in series, used to load aviation kerosene hydrogenation catalysts, which may include hydrogenation protection catalysts and hydrogenation refining catalysts, etc. Specific catalysts can be existing catalysts with the same function. The hydrogenation catalyst generally includes a support component and a hydrogenation active metal component, wherein the hydrogenation active metal component includes Group VIB metal elements and / or Group VIII metal elements, wherein the Group VIB loading metal element is Mo and / or W, and the Group VIII metal element is Ni and / or Co. The catalyst gradation method can be carried out according to conventional methods, and is not particularly limited in this invention.

[0015] In the method of this invention, the supplementary hydrogen for purging is the hydrogen used in the normal production process of the jet fuel liquid phase hydrogenation unit, which is mainly used for hydrogenation to remove impurities from jet fuel raw materials.

[0016] In the method of the present invention, the purging operation conditions in step (2) are as follows: pressure 0.3-4.0 MPa, temperature 20-80°C, hydrogen quantity is the maximum designed amount to be fed into the device, and purging time is 4-6 hours.

[0017] In the method of the present invention, the nitrogen purging time in step (3) is 4 to 8 hours.

[0018] In the method of the present invention, the bottom effluent of the reactor described in step (3) enters the low-pressure separator for separation, and the hydrogen and fuel gas are recycled and reused at the top of the gas-liquid separator.

[0019] Compared with the prior art, the method of the present invention has the following advantages:

[0020] 1. Compared to the shutdown process of conventional jet kerosene hydrogenation, this invention only requires the installation of some pipelines and valves to complete the catalyst oil carry-over process during the shutdown of the liquid-phase hydrogenation unit within 10-18 hours, slightly longer than the time required for conventional jet kerosene hydrogenation units. Existing jet kerosene liquid-phase hydrogenation units require at least 24-36 hours to achieve the same effect during normal shutdown oil carry-over. This invention, by introducing nitrogen and some fuel gas used in the heating furnace, fully utilizes the differences in the molecular structure and flow properties of different gases. Through a synergistic effect, it simultaneously increases the purging gas volume of the catalyst bed, achieving a better catalyst oil carry-over effect. Therefore, this invention, by adding some pipelines and corresponding valves, does not require an additional hydrogen supply from outside the unit.

[0021] 2. In the method of this invention, the fuel gas used is a hydrocarbon mixture gas used in the heater of this unit, which does not require changes to the unit's process flow and has low modification costs. Most of the fuel gas used is used for purging the oil in the catalyst bed of the liquid-phase hydrogenation reactor, while a small portion still enters the heater to heat and supplement hydrogen, nitrogen, and the fuel gas entering the reactor. This method solves the problem of low gas volume in the catalyst bed and ensures that hydrogen, nitrogen, and fuel gas can enter the catalyst bed at higher temperatures, improving the purging and oil removal effect. In addition, since the main components of the fuel gas include hydrogen, methane, ethane, and small amounts of propane and butane, the smaller molecular weight hydrogen and methane can effectively purge the oil in the catalyst micropores, while the relatively larger molecular weight ethane, propane, and butane can effectively carry the oil between catalyst particles out of the hydrogenation reactor. Through the synergistic effect of gases with different molecular weights, the removal of oil in and between catalyst pores is effectively guaranteed.

[0022] 3. The method of this invention fully utilizes the synergistic effect of nitrogen, hydrogen, and fuel gas. During the first purging process, the main function of the heated nitrogen, hydrogen, and fuel gas is to purge the oil remaining in the pores and between particles of the catalyst in the upper bed of the reactor. At the same time, the oil remaining in the upper bed of the catalyst flows downward into the lower bed due to its own weight. During the second purging process, the heated nitrogen and fuel gas continue to purge the small amount of residual oil remaining in the pores and between particles of the catalyst in the upper bed of the reactor, and then enter the lower catalyst bed. Hydrogen is directly introduced into the top of the lower catalyst bed, which greatly reduces the resistance generated by the upper catalyst bed and can purge some of the oil remaining in the micropores and between particles of the catalyst in the lower bed of the reactor better and faster. At the same time, the nitrogen and fuel gas coming from the upper part can also play a synergistic purging effect with hydrogen, and finally carry all the oil remaining in the catalyst bed out of the hydrogenation reactor. Because the three gases have different molecular structures and fluidity, they can effectively remove the oil stored in the micropores and between particles of the catalyst. Moreover, the temperature is relatively high and the flow rate of the mixed gas is relatively large, so the oil stored in the catalyst bed can be removed more quickly and effectively.

[0023] 4. In the method of the present invention, the fuel gas used in the heating furnace of the device is fully utilized, so that it can not only play the role of heating gas, but also fully play the role of purging the oil in the catalyst bed. At the same time, it plays a good synergistic purging role with hydrogen and nitrogen, which effectively solves the problem of long downtime of aviation kerosene liquid phase hydrogenation unit. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a specific process of the method of the present invention.

[0025] Among them: 1-jet fuel, 2-fuel oil buffer tank, 3-feed pump, 4-fuel heater, 5-gas-liquid mixer, 6-liquid phase hydrogenation reactor, 7-low pressure separator, 8-fractionation tower, 9-refined kerosene, 10-nitrogen, 11-supplementary hydrogen, 12-fuel gas, 13-valve a, 14-valve b, 15-valve c, 16-valve d, 17-valve e, 18-valve f. Detailed Implementation

[0026] The method of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, one implementation of the shutdown treatment method for the liquid-phase hydrogenation unit of aviation kerosene according to the present invention is as follows: First, appropriately reduce the temperature of the raw material heater 4, cut off the aviation kerosene raw material 1, close valves 17e and f18, open valves b14, c15 and d16, and introduce nitrogen 10, supplementary hydrogen 11 and part of the fuel gas 12 from before the heater, after being heated, through the gas-liquid mixer 5, and enter from the top of the liquid-phase hydrogenation reactor 6. After 2 to 4 hours, close valve d16, slowly open valve f18, and supplementary hydrogen 11 through valve f18. 18 enters the top of the lower catalyst bed in the liquid phase hydrogenation reactor 6 and passes through the lower catalyst bed from top to bottom. At this time, the heated nitrogen gas 10 and fuel gas 12 still pass through the catalyst bed in the liquid phase hydrogenation reactor 6 from top to bottom. After 4 to 6 hours, valve b14 is slowly closed, followed by valve f18. Nitrogen continues to purge the reactor until the hydrocarbon combustible gas analysis is qualified. The hydrogen and fuel gas used in the purging process can be discharged from the top of the low-pressure separator 7 and returned to the gas pipeline network for continued use or purified hydrogen for reuse.

[0028] The following examples will further illustrate the present invention.

[0029] In the embodiments and comparative examples of this invention, the liquid-phase hydrogenation technology for aviation kerosene developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., the FH-40B hydrogenation catalyst, and the FZC series hydrogenation protectant were used to conduct shutdown tests on the liquid-phase hydrogenation unit for aviation kerosene.

[0030] The hydrorefining catalyst used in the embodiments and comparative examples of this invention is the FH-40B hydrorefining catalyst developed and produced by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd., and its physicochemical properties are shown in Table 1. The residual oil content of the catalyst was determined using an RPA-03 catalyst volatiles simulation analyzer.

[0031] Example 1

[0032] according to Figure 1The liquid-phase hydrogenation process for aviation kerosene was adopted. First, the feed temperature to the liquid-phase hydrogenation reactor was reduced to 230℃, then the reaction pressure was slowly reduced to 1.8 MPa, and the feedstock oil supply was stopped. Valves 17 and 18 were closed, while valves 14, 15, and 16 were opened. Nitrogen 10, supplementary hydrogen 11, and part of the fuel gas 12 were introduced through heater 4, heated, and then passed through gas-liquid mixer 5, entering from the top of the liquid-phase hydrogenation reactor 6. After 3 hours, valve 16 was closed, and valve 18 was slowly opened. Supplementary hydrogen 11 entered the top of the lower catalyst bed in the liquid-phase hydrogenation reactor 6 through valve 18, flowing downwards through the lower catalyst bed. At this time, the heated nitrogen 10 and fuel gas 12 continued to flow downwards through the catalyst bed in the liquid-phase hydrogenation reactor 6. After 5 hours, valve 14 was slowly closed, followed by valve 18. Nitrogen continued to purge the reactor for 4 hours until the hydrocarbon combustible gas analysis was satisfactory, ending the entire shutdown process. The results after shutdown are shown in Table 3.

[0033] Example 2

[0034] according to Figure 1 The liquid-phase hydrogenation process for aviation kerosene was adopted. First, the feed temperature to the liquid-phase hydrogenation reactor was reduced to 230℃, then the reaction pressure was slowly reduced to 2.0 MPa, and the feedstock was stopped. Valves 17 and 18 were closed, while valves 14, 15, and 16 were opened. Nitrogen 10, supplementary hydrogen 11, and part of the fuel gas 12 were introduced through heater 4, heated, and then passed through gas-liquid mixer 5, entering from the top of the liquid-phase hydrogenation reactor 6. After 4 hours, valve 16 was closed, and valve 18 was slowly opened. Supplementary hydrogen 11 entered the top of the lower catalyst bed in the liquid-phase hydrogenation reactor 6 through valve 18, flowing downwards through the lower catalyst bed. At this time, the heated nitrogen 10 and fuel gas 12 continued to flow downwards through the catalyst bed in the liquid-phase hydrogenation reactor 6. After 5 hours, valve 14 was slowly closed, followed by valve 18. Nitrogen continued to purge the reactor for 6 hours until the hydrocarbon combustible gas analysis was satisfactory, ending the entire shutdown process. The results after shutdown are shown in Table 3.

[0035] Comparative Example 1

[0036] Compared with Example 1, the only difference is that only supplemental hydrogen is used to purge the catalyst bed in the liquid phase hydrogenation reactor.

[0037] Comparative Example 2

[0038] Compared with Example 2, the only difference is that only supplemental hydrogen is used to purge the catalyst bed in the liquid phase hydrogenation reactor, and the purging time is basically the same as that of this technical solution.

[0039] Table 1 Physicochemical properties of hydrorefining catalysts

[0040]

[0041]

[0042] Table 2 Fuel Gas Group Composition

[0043] name,% Fuel gas A Fuel gas B hydrogen 2.4 5.1 methane 18.8 25.2 Ethane 20.1 23.3 ethylene 0.4 0.2 propane 23.6 21.1 propylene 0.5 0.8 butane 34.1 24.0 Butene 0.1 0.3 total 100.0 100.0

[0044] Table 3. Effects of shutdown in the examples and comparative examples

[0045]

[0046]

Claims

1. A method for handling the shutdown of a liquid-phase hydrogenation unit for aviation kerosene, characterized in that... The following are included: (1) First, reduce the feed temperature of aviation kerosene. When the temperature is reduced, stop feeding aviation kerosene. Supplement hydrogen is introduced into the liquid phase hydrogenation reactor from the front of the heater. At the same time, nitrogen and some fuel gas are introduced into the front of the heater. The mixed gas of heated nitrogen, hydrogen and some fuel gas enters the catalyst bed from the top of the liquid phase hydrogenation reactor to purge the catalyst bed; (2) Introduce the maximum amount of supplement hydrogen into the hydrogen supply line between the beds of the liquid phase hydrogenation reactor and purge the catalyst bed from the middle and lower part of the reactor; (3) Close the fuel gas bypass valve of the heater. The fuel gas no longer enters the heater and the liquid phase hydrogenation reactor. Close the supplement hydrogen and continue to purge and replace the reactor with nitrogen for 4 to 8 hours. The hydrocarbon oil in the catalyst bed is discharged from the bottom of the reactor.

2. The method according to claim 1, characterized in that: Step (1) involves lowering the feed temperature to 210-280°C or 10-30°C below the final reaction temperature.

3. The method according to claim 1, characterized in that: The fuel gas mentioned in step (1) is a mixed gas supplied to the heating furnace of this device. Its main components include hydrogen, methane, ethane and a small amount of propane and butane. The fuel gas introduced into the liquid phase hydrogenation reactor accounts for 30% to 80% of the total fuel gas in the feed heating furnace. The remaining fuel gas is still used as fuel for the heating furnace to heat the mixed gas.

4. The method according to claim 1, characterized in that: In the mixed gas described in step (1), the proportion of nitrogen is 15-30%, the proportion of fuel gas is 15-30%, and the proportion of supplemented hydrogen is 40-70%.

5. The method according to claim 1, characterized in that: The purging conditions for step (1) are as follows: pressure 0.3~4.0MPa, temperature 200~350℃, gas-agent volume ratio 50~200, and purging time 2~4 hours.

6. The method according to claim 1, characterized in that: The liquid-phase hydrogenation reactor described in step (1) includes a feed oil buffer tank, a feed pump, a feed heater, a gas-liquid mixer, a liquid-phase hydrogenation reactor, a low-pressure separator, a fractionation tower, and corresponding pipelines and valves; wherein, the liquid-phase hydrogenation reactor is a multi-bed fixed-bed hydrogenation reactor; the liquid-phase hydrogenation reactor is used as a single reactor or multiple reactors connected in series to fill the aviation kerosene hydrogenation catalyst.

7. The method according to claim 1, characterized in that: The supplementary hydrogen used for purging is the hydrogen gas used in the normal production process of the aviation kerosene liquid phase hydrogenation unit, which is used to remove impurities from the aviation kerosene feedstock.

8. The method according to claim 1, characterized in that: The purging operation conditions for step (2) are as follows: pressure 0.3~4.0MPa, temperature 20~80℃, hydrogen quantity is the maximum designed amount to be introduced into the device, and purging time is 4~6 hours.

9. The method according to claim 1, characterized in that: The nitrogen purging time in step (3) is 4 to 8 hours.

10. The method according to claim 1, characterized in that: The bottom effluent from the reactor described in step (3) enters a low-pressure separator for separation, while hydrogen and fuel gas are recycled and reused at the top of the gas-liquid separator.

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